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August 27, 1995
Gamma Ray Bursts from the Unknown
Credit:
NASA,
Compton Gamma Ray Observatory,
BATSE
Explanation:
Gamma Ray Bursts (GRBs) pose one of the greatest mysteries of modern
astronomy. About once a day, the
gamma-ray sky lights up with a
spectacular explosion. No one knows what causes these explosions or even
how far away they are. The above map represents the entire sky
in coordinates centred on our Galaxy,
the Milky Way.
It shows the positions of over 800 of these mysterious bursts
of energy detected by the
BATSE
instrument on board NASA's
Compton Gamma Ray Observatory.
Before BATSE,
most astronomers thought that most GRBs occurred in the disk of our Galaxy,
but the above sky map shows little sign of this. The distance
scale of GRBs was the topic of a
historic
debate in April 1995. The positions in the above map are currently
being studied in great detail in an effort to uncover a clue about
the nature of GRBs.
In the above 3B map created by Robert Nemiroff, spot size is proportional
to peak flux and spot colour is indicative of hardness.
Click here for a postscript version
of BATSE's latest map of
1122 GRB locations (3B Catalogue).
Tomorrow's picture: Dusty Galaxy Centaurus A
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Authors & editors:
Robert Nemiroff
(MTU) &
Jerry
Bonnell (USRA)
NASA Technical Rep.:
Jay Norris.
Specific rights apply.
A service of:
LHEA
at
NASA/
GSFC
&:
Michigan Tech. U.